1. Field
The present disclosure relates generally to electrical power systems, such as systems for providing electrical power for motors and other loads on an aircraft. The present disclosure relates more specifically to alternating current power systems equipped with direct current power conversion equipment for providing electrical power to direct current loads and to identifying conditions in such power systems and protecting such systems from undesired conditions in a coordinated manner.
2. Background
Aircraft may employ various electronic devices and systems to perform various functions on the aircraft. For example, without limitation, electric motors on an aircraft may be used to move flight control surfaces, to pressurize hydraulics, to pump fuel, and to perform other functions on the aircraft. Power for the electric motors and other electronic systems and devices on an aircraft may be provided by an aircraft power system.
Power systems in modern aircraft may be different from both traditional ground-based electrical utility power systems and traditional aircraft power systems in several ways. For example, without limitation, power systems in modern aircraft may employ direct current (DC) buses to power electric motors, motor controllers for the electric motors, and other DC loads on the aircraft. Power for the DC buses may be provided via a power converter configured to convert alternating current (AC) power on an AC bus to DC power on the DC buses. AC power is provided on the AC bus by a generator on the aircraft. On modern aircraft, the generated AC power is mainly consumed by loads connected to the DC buses and not by traditional AC loads. Voltage levels on the DC buses may be selected to reduce currents and weight associated with power distribution on the aircraft.
It is desirable to protect the components of an aircraft power system from undesirable conditions that may occur on the power system. However, due to the differences between traditional aircraft power systems and more modern systems, the methods for providing power system protection in traditional systems may not be used to provide the desired protection for more modern aircraft power systems.
Accordingly, it would be desirable to have a method and apparatus that takes into account one or more of the issues discussed above as well as possibly other issues.